It is known to equip a host-vehicle with a radar system for detecting objects such as other vehicles proximate to the host-vehicle. Such object detection is desirable for detecting, for example, other vehicles in the so called blind spot which is not readily observable by an operator of a vehicle using typical side-view and rear-view mirrors. Such object detection may also be useful to warn the operator of a rapidly approaching vehicle in an adjacent lane if the operator indicates that a lane-change is about to be executed by, for example, activating a turn-signal indicator, or for detecting objects behind the host vehicle when backing-up. If the host vehicle is towing a trailer, reflections of radar signals by the trailer system may interfere with the detection of a target that does not correspond to or is not associated with the trailer. The accurate determination of the trailer-size is essential for distinguishing the trailer from other targets.